A variety of applications employ fluid filter assemblies. Such applications include, for example, hydraulic systems, fuel delivery systems, coolant systems, and engine lubrication systems. Filter assemblies may be used to filter any type of fluid, such as, for example, gasoline, diesel fuel, lubricating oil, water, coolant fluid, and others. For example, a filter assembly may filter out contamination from a coolant fluid that flows from a cooler tank and ultimately through a heat exchanger as part of a refrigeration system, air conditioning system, or other suitable cooling system as are known in the art.
Conventional fluid filter assemblies may include a filter media, such as a sheet of fibrous filter material folded to form a plurality of parallel pleats or folds. The side edges of the sheet are brought together so that the sheet has a cylindrical configuration, with the pleats of the sheet extending in the axial or longitudinal direction. The side edges of the sheet are then joined together, such as with adhesive, stitching or other means, to retain the filter material in the cylindrical form. The media can be imparted with resin, and/or an outer or inner wire mesh sheet, weave, or mesh cage for enhanced durability, if warranted or desirable. The reinforcement provided by such structures prevents the pleats from bunching, prevents media migration, and maintains media efficacy.
As the filter is used, contaminants may be build up within the filter media, which impedes or restricts the fluid flow. With the flow restricted, undesirable pressure may build up within the filter and clog the filter, which can result in damage to the system in which the filter is incorporated. Accordingly, a filter assembly may include a pressure bypass relief valve to permit fluid flow out of the filter assembly in the event of high pressures stemming from restricted fluid flow through the filter media. An indicator light or comparable device may be provided to alert a user of a need to change the filter assembly.
Coolant fluid that flows through refrigeration systems, air conditioning systems, and similar cooling systems including a heat exchanger presents particular issues with respect to fluid flow through a filter assembly. The coolant fluid may be subjected to temperature variations throughout the system. Typically, coolant fluid is maintained initially in a cooler tank. The coolant fluid is pumped through the cooling system to remove heat from the system for cooling. The heated coolant fluid next flows through a heat exchanger that is employed to remove excess heat from the coolant fluid, which is then returned as cooled fluid to the cooler tank. The coolant fluid typically may be filtered at the entrance port to the cooler tank. Accordingly, the temperature of the coolant fluid at the filter assembly is significant, but control of fluid flow through the filter assembly based on temperature has not been adequately addressed by conventional filter assemblies.